In embodiments described herein, the following understanding of the nomenclature used in describing the present High Capacity Energy Storage Capacitors should be understood and considered. In older literature, the term “dielectric constant” of a material is used to describe the polarization ability or “permittivity” of the material when placed in an electric field. The term “dielectric breakdown” was used to describe the voltage at which an insulator material would “breakdown” and conduct current. This dielectric breakdown voltage is also known as the dielectric strength. Since the abbreviated version for both of these terms is “dielectric,” and the material itself is called the dielectric, there was some confusion in the literature as to what was being discussed. Thus, the term “permittivity” is now used (mostly) to describe the ability of a material to charge polarize and change the “dielectric constant” of its volume of space to a higher value from that of a vacuum. Dielectric breakdown voltage is sometimes used to indicate the dielectric strength of the material.
The relative permittivity of a material is simply the measurement of its static dielectric constant divided by the dielectric constant of vacuum.
      e    r    =            e      s              e      0      
where:                er=relative permittivity        es=measured permittivity        eo=electrical permittivity of vacuum (8.8542 E−12 F/m)        
Thus, when the term good dielectric is used, this is meant (usually) to mean a material that displays good electrical insulation characteristics such as a high breakdown voltage and a low conductivity. A material that has a good “dielectric constant” for a capacitor means it has a good “permittivity” (high value) and increases the capacitance of a given size capacitor when placed between the electrodes by a “good” (high) amount.
A capacitor is formed when two conducting plates are separated by a non-conducting media, called the dielectric. The value of the capacitance depends on the size of the plates, the distance between the plates and the properties of the dielectric. The relationship is:
  C  =                              e          0                ·                  e          r                    ⁢      A        d                  eo=electrical permittivity of vacuum (8.8542 E−12 F/m)        er=relative permittivity        A=surface of one plate (both the same size)        d=distances between two plates        
Whereas the electrical permittivity of a vacuum is a physical constant, the relative electrical permittivity depends on the material.
Typical Relative Electrical PermittivitiesMaterialerVacuum1Water80.1 (20° C.)Organic Coating4-8
A large difference is noticed between the electrical permittivity of water and that of an organic coating.
Relative static permittivities ofsome materials at room temperatureMaterialDielectricVacuum1(by definition)Air1.00054Polytetrafluoroethylene2.1Polyethylene2.25Polystyrene2.4-2.7Paper3.5Silicon dioxide3.7Concrete4.5Pyrex (glass)4.7 (3.7-10)Rubber7Diamond5.5-10 Salt 3-15Graphite15 Oct.Silicon11.68Methanol30Furfural42Glycerol47-68Water88-80.1-55.3-34.5Hydrofluoric acid83.6 (0° C.)Formamide84.0 (20° C.)Sulfuric acid84-100 (20-25° C.)Hydrogen peroxide128 aq-60 (−30-25° C.)Hydrocyanic acid158.0-2.3 (0-21° C.)Titanium dioxide 86-173Strontium titanate310Barium strontium15 nc-500Barium titanate90 nc-1250-10,000(La Nb):(Zr Ti)PbO3500, 6000
It is interesting to note that materials which have large dipole moments and high permittivity are often conductive salts or very polar inorganic acids or bases. In these cases their liquid form is difficult to use and/or toxic or corrosive. This makes their utility difficult and dangerous. Often the polar salts display undesirable conductivity when they are slightly impure and/or exposed to atmospheric conditions with humidity.
The inorganic salts which display nonconductive behavior and very high permittivities are inorganic salts of the transition metals and other inorganic salts that display high permittivities due to their crystal lattice structures. Use of these materials are difficult due to their crystalline nature. Much effort has been expended to make these types of material more manufacturable through the use of thin coatings and methods of high temperature fusing and sintering.